Anatomical Heart Puzzle

It’s not easy to fix a broken heart. Model displayed is printed in temperature sensitive colour changing filament.

See here for video: https://youtu.be/nYwyI-LPaII

See here for stable download: https://social.thangs.com/m/693398

This puzzle is part of the family of different “6-Piece Burr Puzzle” configurations. This is a “Level 1” design because one piece needs to be moved (“unlocked”) before you can begin to disassemble the puzzle. Taking it apart is tricky, but putting it back together is much harder!

Can’t figure out how to fit the pieces fit together?
See here for an instructional model: https://social.thangs.com/m/617380
And here for an instructional video: https://youtu.be/UcFXx5P6eX4

Similar puzzles:
Ripple Ball Burr Puzzle: https://social.thangs.com/m/617381
Valentine’s Heart Puzzle: https://social.thangs.com/m/639563